Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
import sys
from collections import deque
readline=sys.stdin.readline
read=sys.stdin.read

h,w=map(int,readline().split())
wb={'#':0,'.':1}
s=[wb[g] for g in read() if g!='\n']
dist=[0]*(h*w)
dist[0]=1
stack=deque([(0,0)])
while stack:
  cg=stack.popleft()
  for i in range(4):
    ng=(cg[0]+(1-2*(i&1))*(i>>1),cg[1]+(1-2*(i&1))*(1-(i>>1)))
    fcg=w*cg[0]+cg[1]
    fng=w*ng[0]+ng[1]
    if 0<=ng[0]<=h-1 and 0<=ng[1]<=w-1 and \
        s[fng] and dist[fng]==0:
      stack.append(ng)
      dist[fng]=dist[fcg]+1
if dist[-1]:
  print(sum(s)-dist[-1])
else:
  print(-1)